Selection of raw materials suitable for pyrolysis plant

The selection of raw materials for pyrolysis oil refining equipment is centered on adapting to the process characteristics of high temperature resistance, corrosion resistance and coking resistance. Materials should be selected specifically according to the working conditions (temperature, pressure, type of medium contact) of different equipment parts, which are mainly divided into three categories: core reaction components, auxiliary process components, and structural support components. Details are as follows:

Raw Materials for Core Reaction Components (in direct contact with high-temperature pyrolysis materials)

These components are the core of the equipment, which need to withstand high temperatures of 400–600℃, oil-gas corrosion and material friction, making them the focus of material selection:

Pyrolysis reactor shell/tubes: Heat-resistant stainless steel is preferred, such as 310S stainless steel (resistant to high-temperature oxidation, with a long-term service temperature up to 1150℃) and 2520 duplex stainless steel (featuring both high-temperature resistance and corrosion resistance). For large-scale continuous reactors, chromium-nickel alloys (e.g., Inconel series) can be adopted, which are suitable for ultra-high temperature and high-pressure working conditions and can effectively prevent coking and oxidation deformation.

Stirring paddles/material conveying augers: Wear-resistant and heat-resistant alloy cast iron or nitrided 304 stainless steel are selected to enhance wear resistance and avoid component loss caused by high-speed friction of materials.

Raw Materials for Auxiliary Process Components (medium treatment, heat exchange, separation processes)

These components are in contact with oil and gas, condensate, acid-base solutions and other media, with a focus on corrosion resistance, sealing performance and heat exchange efficiency:

Condensers/fractionation towers: The condensation section is in contact with high-temperature oil-gas and low-temperature coolant, so 304/316L stainless steel is selected (316L has better corrosion resistance to acidic substances in condensate). The internal parts of fractionation towers (trays, packing) can use carbon steel + anti-corrosion coating (e.g., epoxy resin coating) to reduce costs while ensuring corrosion resistance.

Tail gas treatment equipment (desulfurization towers, caustic washing towers): These equipment are in contact with acidic gases (e.g., hydrogen sulfide, hydrogen chloride) and alkaline washing liquid, so FRP (fiber-reinforced plastic) or PP (polypropylene) are preferred, which are lightweight, acid and alkali resistant, more economical and durable than metal materials. For gas pipelines, 316L stainless steel pipes or plastic-lined carbon steel pipes are prioritized.

Raw material pretreatment equipment (crushers, dryers): The crusher cavity is made of high manganese steel (impact and wear resistant); the dryer shell is made of carbon steel (low cost, no severe corrosion conditions), and the inner wall can be coated with anti-rust paint to extend service life.

Raw Materials for Structural Support Components (load-bearing and frame components)

These components have no direct contact with process media, with a focus on mechanical strength and cost-effectiveness:

Equipment frames, bases and shells: Q235 carbon steel (plain carbon steel plates/sections) is selected, which meets the load-bearing requirements in terms of mechanical strength and is low-cost. The surface can be treated with paint spraying or hot-dip galvanizing for rust prevention.

Pipe supports and operating platforms: Carbon steel sections such as channel steel and I-beam are adopted, which can be welded and then subjected to anti-corrosion treatment.